There are many safety syringe designs available today. All of these designs that have various types of latching devices are Z. M. Roehr et al U.S. Pat. No. 3,008,570, Z. M. Roehr U.S. Pat. No. 3,107,785, Bartner, et al U.S. Pat. No. 3,895,633, G K Burke U.S. Pat. No. 3,306,291, Gyure et al U.S. Pat. No. 4,300,678, Winstead Hall U.S. Pat. No. 6,356,822, Sampson U.S. Pat. No. 4,425,120, Larson U.S. Pat. No. 4,639,249, Harbaugh U.S. Pat. No. 4,655,751, Strauss U.S. Pat. No. 4,664,654, Braginetz U.S. Pat. No. 466,435, Spencer U.S. Pat. No. 4,702,738, Milorad U.S. Pat. No. 4,702,739, Spencer U.S. Pat. No. 4,801,295, Poncy U.S. Pat. No. 4,815,022, and Hughes U.S. Pat. No. 4,840,619.
Other designs have a retractable needle such as Weltman U.S. Pat. No. 3,306,290, and Dent U.S. Pat. No. 4,392,859. These designs do not have a means whereby the needle is extended from the syringe and held in place in a positive and rigid position in order to first inject the needle prior to injecting the medication. Still other designs have methods of bending the needle to render it harmless after the medication has been injected. Most of these designs have one major purpose and that is to prevent the spread of infectious diseases such as aids, hepatitis, or other diseases from an accidental injection with a contaminated needle into others after the needle of the syringe has been inserted into a patient with the above mentioned diseases. These various designs all work well up to a degree, but they all fall short of their intended purpose during the act of covering the needle, or removing the needle, which requires two hands.
Other devices such as Tsao U.S. Pat. No. 5,019,044, Tsao U.S. Pat. No. 5,084,018, Shaw U.S. Pat. No. 5,267,961, Shaw U.S. Pat. No. 5,389,076, Shaw U.S. Pat. No. 5,385,551, Shaw U.S. Pat. No. 5,120,310, Dysarz U.S. Pat. No. 4,978,343, and Dysarz U.S. Pat. No. 4,973,316 are capable of releasing the needle cannula if the container that they are packaged in is dropped or jarred severely. These devices do not have a positive latching means but they rely on friction to restrain the needle cannula with the biased spring.
All of these designs also combine the needle cannula with the syringe and therefore create a storage problem. At present, needle cannulas are fixed to the hub but not to the syringe so that a variety of lengths and gauges of needle cannulas are stored in one locker or storage cabinet which may contain about twenty various lengths and gauges of needle cannulas; an inventory of about twenty or more of each gauges and lengths of needle cannulas may be stored in each section. There may also be about ten sizes of syringes with about twenty or more of each syringe stored in the same locker. When a given quantity of a given medicament is required, the proper size of needle cannula is fitted to the proper syringe thereby combining the right length and gauge of needle cannula with the right size of syringe.
All of the above inventions would require an inventory ten times of that of the present invention. Each needle cannula size would have to be fixed to each syringe size and each syringe size would have to be fixed to each needle cannula size and this would be hundreds of needle cannula syringe combinations which would be multiplied by ten each the numbers required for the necessary inventory in a given floor of a hospital would be astronomical. The need has developed for a safety needle cannula that would be a module apart from the syringe.